Transparent conductive film, method for production thereof and touch panel therewith

ABSTRACT

A transparent conductive film includes a transparent film substrate; and a first and second crystalline transparent conductive laminate, wherein the second crystalline layer is located between the transparent film substrate and the first transparent conductive layer, and a second content of the tetravalent metal element oxide of the second transparent conductive layer is higher than a first content of the tetravalent metal element oxide of the second transparent conductive layer. The transparent conductive film allows a reduction in crystallization time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a transparent conductive film havingtransparency in the visible light region and including a film substrateand a transparent conductive laminate that is provided on the filmsubstrate and includes at least two transparent conductive layers. Theinvention also relates to a touch panel having such a transparentconductive film. The transparent conductive film of the invention isused for transparent electrodes in touch panels or displays such asliquid crystal displays and electroluminescence displays and also usedfor electromagnetic wave shielding or prevention of static buildup ontransparent products. According to position detection method, touchpanels may be classified into optical, ultrasonic, capacitance, andresistive touch panels. The transparent conductive film of the inventionis suitable for use in capacitance touch panels, specifically,projection-type capacitance touch panels.

2. Description of the Related Art

Concerning a conventional transparent conductive film, the so-calledconductive glass is well known, which includes a glass substrate and atransparent conductive layer of indium oxide formed thereon.Unfortunately, it has low flexibility or workability and cannot be usedin some applications because the substrate is made of glass.

In recent years, therefore, various plastic films including polyethyleneterephthalate films have been used to form substrates because of theiradvantages such as good impact resistance and light weight as well asflexibility and workability, and there has been used a transparentconductive film including a transparent conductive layer of indium oxideformed on such substrates.

Such a transparent conductive layer is often crystallized to meetrequirements such as low resistance, high transmittance, and highdurability. The crystallization method generally includes forming anamorphous transparent conductive layer on a film substrate and thencrystallizing the amorphous transparent conductive layer by heating orany other method. Unfortunately, when such a transparent conductive filmis produced, it is generally difficult to heat the film substrate to200° C. or higher during the crystallization, depending on the heatresistance of the film substrate. Thus, there is a problem in which thetime required to crystallize the transparent conductive layer is longerin the case where the transparent conductive film is produced with afilm substrate than in the case where the transparent conductive layeris formed on a glass substrate and crystallized by heating at hightemperature.

To solve the crystallization time problem and to satisfy reliability athigh temperature and high humidity, it is proposed that transparentconductive layers having a two-layer structure should be formed on afilm substrate. For example, it is proposed that a thin film of anindium-tin complex oxide with a low tin oxide content should be formedon the film substrate side and another thin film of an indium-tincomplex oxide with a high tin oxide content should be formed thereon(JP-A 2006-244771).

SUMMARY OF THE INVENTION

According to JP-A 2006-244771, the crystallization time is reduced tosome extent as compared with the case where a single transparentconductive layer is formed. However, there has been a demand for afurther reduction in the time for the crystallization of transparentconductive layers.

As mentioned above, transparent conductive films are used as transparentelectrodes for touch panels or displays. Projection-type capacitancetouch panels have rapidly spread because they enable multi-touch inputor gesture input and can be installed in smartphones. Suchprojection-type capacitance touch panels have a structure in which apair of transparent conductive films each having a patterned transparentconductive layer are opposed to each other, and in which the capacitancebetween the upper and lower transparent conductive layers (or voltageamplitude, frequency, or the like) is measured while a current isallowed to flow through the transparent conductive films. When an objectsuch as a finger is put closer to the upper-side transparent conductivefilm of a projection-type capacitance touch panel, the capacitancebetween the upper and lower transparent conductive layers changes, sothat the part to which the object is put closer is detected. It has beendesired that a projection-type capacitance touch panel should beproduced using transparent conductive layers with a low resistance (forexample, a surface resistance of about 150 Ω/square) so that thesensitivity and resolution of the sensor can be improved. Specifically,it has been desired that the specific resistance should be lowered.Unfortunately, a transparent conductive film produced with a filmsubstrate has a problem in which the upper limit of the heatingtemperature for the crystallization of the transparent conductive layeris lower than that in the case where a glass substrate is used, andtherefore, the specific resistance of the crystallized transparentconductive layer is higher in the transparent conductive film than inthe product having the glass substrate. JP-A 2006-244771 discloses thatreliability at high temperature and high humidity can be improved inaddition to a reduction in crystallization time, but the specificresistance of transparent conductive layers cannot be reduced accordingto JP-A 2006-244771.

An object of the invention is to provide a transparent conductive filmthat allows a reduction in crystallization time and has crystallinetransparent conductive layers.

Another object of the invention is to provide a transparent conductivefilm that allows a reduction in crystallization time and a reduction inspecific resistance and has crystalline transparent conductive layers.

A further object of the invention is to provide a touch panel producedusing such a transparent conductive film.

To solve the conventional problems, the inventors have accomplished theinvention based on the finding that the objects can be achieved by thetransparent conductive film and other features described below.

The invention relates to a transparent conductive film, including:

a transparent film substrate; and

a transparent conductive laminate that is provided on at least onesurface of the transparent film substrate and includes a firsttransparent conductive layer and a second transparent conductive layer,wherein

the first transparent conductive layer is a first crystalline layercomprising indium oxide or an indium-based complex oxide having atetravalent metal element oxide,

a first content of the tetravalent metal element oxide of the firsttransparent conductive layer is more than 0% by weight and not more than6% by weight,

the second transparent conductive layer is a second crystalline layercomprising an indium-based complex oxide having a tetravalent metalelement oxide, and located between the transparent film substrate andthe first transparent conductive layer, and

a second content of the tetravalent metal element oxide of the secondtransparent conductive layer is higher than the first content,

wherein each of the first and the second contents of the tetravalentmetal element oxide content is expressed by the formula: {the amount ofthe tetravalent metal element oxide/(the amount of the tetravalent metalelement oxide+the amount of indium oxide)}×100(%).

In the transparent conductive film, it is preferable that there is adifference between the first content and the second content ispreferably 3% by weight or more.

In the transparent conductive film, the second content is preferably 3to 35% by weight.

In the transparent conductive film, a first thickness of the firsttransparent conductive layer is preferably smaller than a secondthickness of the second transparent conductive layer. A differencebetween the first thickness and the second thickness is preferably 1 nmor more.

In the transparent conductive film, the first thickness is preferably 1to 17 nm, and the second thickness is preferably 9 to 34 nm.

The transparent conductive films further may include a third transparentconductive layer that is located between the transparent film substrateand the second transparent conductive layer, and the third transparentconductive layer is a third crystalline layer. The third transparentconductive layer is suitable for use indium oxide or an indium-basedcomplex oxide having a tetravalent metal element oxide, and

a third content of the tetravalent metal element oxide of the thirdtransparent conductive layer is more than 0% by weight and not more than6% by weight,

wherein the third content is expressed by the formula: {the amount ofthe tetravalent metal element oxide/(the amount of the tetravalent metalelement oxide+the amount of indium oxide)}×100(%).

In the transparent conductive film, a total thickness of the transparentconductive laminate is preferably 35 nm or less.

In the transparent conductive film, a ratio of the first thickness tothe total thickness is preferably from 1 to 45%.

In the transparent conductive film, an indium-tin complex oxide may beused as the indium-based complex oxide, and tin oxide may be used as thetetravalent metal element oxide.

In the transparent conductive film, the transparent conductive laminatemay be provided on the film substrate with an undercoat layer interposedtherebetween.

The invention also relates to a method for producing the transparentconductive film, including:

heat-treating a transparent conductive film including a transparent filmsubstrate and a transparent conductive laminate that is provided on atleast one surface of the transparent film substrate and includes a firsttransparent conductive layer and a second transparent conductive layer,so that the first and the second transparent conductive layers in thetransparent conductive film are crystallized, wherein

the first transparent conductive layer is a first amorphous layerincluding indium oxide or an indium-based complex oxide having atetravalent metal element oxide,

a first content of the tetravalent metal element oxide of the firsttransparent conductive layer is more than 0% by weight and not more than6% by weight,

the second transparent conductive layer is a second amorphous layerincluding an indium-based complex oxide having a tetravalent metalelement oxide, and located between the transparent film substrate andthe first transparent conductive layer, and

a second content of the tetravalent metal element oxide of the secondtransparent conductive layer is higher than the first content,

wherein each of the first and the second contents of the tetravalentmetal element oxide content is expressed by the formula: {the amount ofthe tetravalent metal element oxide/(the amount of the tetravalent metalelement oxide+the amount of indium oxide)}×100(%).

The invention also relates to a touch panel, including the transparentconductive.

Conventional transparent conductive layers having a two-layer structureas disclosed in JP-A 2006-244771 include: a thin film of an indium-tincomplex oxide that is provided on the film substrate side and has a lowtin oxide content; and a thin film of an indium-tin complex oxide thatis next to the above thin film and has a high tin oxide content.Crystallization time can be reduced to some extent using the transparentconductive layers with such a two-layer structure, as compared withusing a single transparent conductive layer. Contrary to theconventional structure, the transparent conductive laminate according tothe invention includes: a thin film of indium oxide or an indium-basedcomplex oxide (such as an indium-tin complex oxide) having a low contentof a tetravalent metal element oxide (such as tin oxide), which isprovided on the front surface side; and a thin film of an indium-basedcomplex oxide having a high content of the tetravalent metal elementoxide, which is provided next to the above thin film. Such a structuremakes crystallization time shorter than that for the conventionaltwo-layer structure.

An indium-based complex oxide is generally used for transparentconductive layers. This is because of taking advantage of the fact thatdoping indium oxide with a tetravalent metal element oxide causessubstitution between the trivalent indium and the tetravalent metalelement in the process of forming indium oxide crystals by heating orthe like, so that excess electrons serve as carriers in the resultingcrystalline layer. Therefore, as the content of the tetravalent metalelement oxide in the indium-based complex oxide increases, currentcarriers increase, so that the specific resistance decreases.

On the other hand, as the content of the tetravalent metal element oxideincreases, impurities capable of inhibiting the crystallization ofindium oxide increase. At the same heating temperature, therefore, asthe content of the tetravalent metal element oxide increases, the timerequired for the crystallization increases. It is also considered thatif crystal nuclei can be formed with lower energy, the time required forthe crystallization of indium oxide can be reduced. Therefore, it isconsidered that generating necessary energy for the formation of crystalnuclei is rate-limiting in the crystallization.

It is also considered that gas can be generated from the film substrateto affect the indium oxide thin film formed on the film substrate, andtherefore, the thin film formed at a position more apart from the filmsubstrate (toward the uppermost surface side) can be less defective andmore susceptible to crystallization.

From the foregoing, it is considered that when the process of formingplural transparent conductive layers includes forming an indium-basedcomplex oxide thin film having a high tetravalent metal element oxidecontent and then forming thereon an indium oxide thin film or anindium-based complex oxide thin film having a low tetravalent metalelement oxide content, the thin film located on the front surface sidehas a low content of impurities including the tetravalent metal elementand therefore is susceptible to crystallization, so that the use of sucha structure can reduce the time required to crystallize the amorphoustransparent conductive layers.

It is considered that the effect of the invention to reducecrystallization time is produced by the feature that in the transparentconductive film including plural transparent conductive layers, atransparent conductive layer susceptible to crystallization is placed ata position susceptible to crystallization so that crystal growth in anamorphous transparent conductive layer less susceptible tocrystallization can be facilitated.

As mentioned above, as the content of a tetravalent metal element oxidein an indium oxide material for a transparent conductive layerincreases, current carriers increase, so that specific resistancedecreases. Therefore, it has been considered that a reduction inspecific resistance and a reduction in the content of a tetravalentmetal element content for the purpose of reducing crystallization timeare a trade-off or difficult to achieve at the same time. According tothe invention, however, a reduction in crystallization time and areduction in specific resistance can be achieved at the same time. Inthe transparent conductive film of the invention, the front surface sidetransparent conductive layer of the plural transparent conductive layersis produced using indium oxide or an indium-based complex oxide having alow tetravalent metal element oxide content. It is therefore consideredthat since the front surface side transparent conductive layer containsno tetravalent metal element oxide or has a low tetravalent metalelement oxide content, the rate of substitution of the tetravalent metalelement is rather increased by the acceleration of crystallization, sothat the specific resistance can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing a transparentconductive film according to an embodiment of the invention;

FIG. 2 is a schematic cross-sectional view showing a transparentconductive film according to an embodiment of the invention;

FIG. 3 is a schematic cross-sectional view showing a transparentconductive film according to an embodiment of the invention;

FIG. 4 is a schematic cross-sectional view showing a transparentconductive film according to an embodiment of the invention;

FIG. 5 is a schematic cross-sectional view showing an exemplary sensorpart of a projection-type capacitance touch panel produced using atransparent conductive film according to an embodiment of the invention;

FIG. 6 is a schematic cross-sectional view showing an exemplary sensorpart of a projection-type capacitance touch panel produced using atransparent conductive film according to an embodiment of the invention;

FIG. 7 is a schematic cross-sectional view showing a laminate producedusing a transparent conductive film according to an embodiment of theinvention; and

FIG. 8 is a schematic cross-sectional view showing an exemplaryresistive touch panel produced using a transparent conductive filmaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention are described below with reference to thedrawings. It should be noted that some parts unnecessary for explanationare omitted, and some parts are illustrated in an enlarged, reduced ormodified form for easy understanding.

FIGS. 1 to 3 are each a schematic cross-sectional view showing anexample of the transparent conductive film (A) according to anembodiment of the invention. Every one of the transparent conductivefilms (A) includes a transparent film substrate (1) and a transparentconductive laminate (2) that includes at least two transparentconductive layers and is formed on one surface of the transparent filmsubstrate (1). All of the transparent conductive layers include indiumoxide or an indium-based complex oxide having a tetravalent metalelement oxide. The transparent conductive laminate (2), which includesat least two transparent conductive layers, may include three or moretransparent conductive layers. While FIGS. 1 to 3 each show that thetransparent conductive laminate (2) is provided on only one surface ofthe transparent film substrate (1), a transparent conductive layer mayalso be provided on the other surface of the film substrate (1). Asingle or two or more transparent conductive layers may also be providedon the other surface, and such two or more transparent conductive layersmay form the same structure as those of the transparent conductivelaminate (2).

FIG. 1 shows a case where in the transparent conductive film (A), thetransparent conductive laminate (2) has two transparent conductivelayers, and the transparent conductive laminate (2) includes: a firsttransparent conductive layer (21) that is located first from itsuppermost surface and made of indium oxide or an indium-based complexoxide having a tetravalent metal element oxide content of more than 0%by weight and not more than 6% by weight, wherein the tetravalent metalelement oxide content is expressed by the formula: {the amount of thetetravalent metal element oxide/(the amount of the tetravalent metalelement oxide+the amount of indium oxide)}×100(%); and a secondtransparent conductive layer (22) that is located second from theuppermost surface and made of an indium-based complex oxide having atetravalent metal element oxide content higher than that of the firsttransparent conductive film (21).

FIG. 2 shows a case where in the transparent conductive film (A), thetransparent conductive laminate (2) includes three transparentconductive layers, and the transparent conductive laminate (2) includesa first transparent conductive layer (21) located first from itsuppermost surface, a second transparent conductive layer (22) locatedsecond from its uppermost surface, and a third transparent conductivelayer (23) located third from its uppermost surface. The case in FIG. 2has one additional layer, which is the third transparent conductivelayer (23), as compared with the case in FIG. 1. The third transparentconductive layer (23) is located first from the transparent filmsubstrate (1).

FIG. 3 shows a case where the transparent conductive laminate (2) asshown in FIG. 1 is provided on the film substrate (1) with an undercoatlayer (3) interposed therebetween. In the mode shown in FIG. 2, anundercoat layer (3) may also be provided as shown in FIG. 3.

FIG. 4 shows a case where the transparent conductive film (A) as shownin FIG. 1 is configured to have the transparent conductive laminate (2)placed on one surface of the film substrate (1) and to have atransparent pressure-sensitive adhesive layer (4) placed on the othersurface. While FIG. 4 shows a case where the transparent conductive film(A) shown in FIG. 1 is used to form a transparent conductive laminate,the transparent conductive film (A) shown in FIG. 2 or 3 or acombination thereof may also be used alternatively.

FIGS. 5 and 6 are schematic cross-sectional views each showing anexemplary sensor part of a projection-type capacitance touch panelformed using the transparent conductive film (A). While FIGS. 5 and 6each illustrate a case where the transparent conductive film (A) shownin FIG. 1 is used, the transparent conductive film (A) of FIG. 2 or 3 ora combination thereof may also be used alternatively. FIGS. 5 and 6 eachshows a structure in which the transparent conductive films (A) shown inFIG. 1 are opposed to each other with a pressure-sensitive adhesivelayer (4) interposed therebetween. In FIG. 5, the film substrates (1) ofthe transparent conductive films (A) are bonded together with thepressure-sensitive adhesive layer (4) interposed therebetween. In FIG.6, the film substrate (1) of one of the transparent conductive films (A)is bonded to the other transparent conductive film (A) with thetransparent conductive laminate (2) interposed therebetween. In FIGS. 5and 6, the transparent conductive laminate (2) (the transparentconductive layers (21) and (22)) has undergone a patterning process. InFIGS. 5 and 6, the transparent conductive film (A) may be placed to faceany one of the upper and lower directions. The sensor part of the touchpanel shown in FIG. 6 or 7 functions as a transparent switch substratein which when an object such as a finger is brought close to thetransparent conductive laminate (2), the on state is produced as aresult of the measurement of an electric signal change caused by changesin the capacitance values on the upper and lower sides, and when theobject such as the finger is taken away, the original off state isrecovered.

FIG. 7 shows a case where a single layer of a transparent substrate film(5) is placed on the pressure-sensitive adhesive layer (4), which isprovided on the transparent conductive film (A) as shown in FIG. 4.Alternatively, two or more layers of transparent substrate films (5) maybe placed through the pressure-sensitive adhesive layer (4). In the caseshown in FIG. 7, a hard coat layer (resin layer) (6) is also provided onthe outer surface of the substrate film (5). While FIG. 7 shows a casewhere the transparent conductive film (A) shown in FIG. 1 is used toform a transparent conductive laminate, the transparent conductive film(A) of FIG. 2 or 3 or a combination thereof may be used alternatively.The laminate having the transparent conductive film (A) of FIG. 7, whichis generally used to form a resistive touch panel, may also be used toform a sensor part of a projection-type capacitance touch panel as shownin FIG. 5 or 6.

FIG. 8 is a schematic cross-sectional view schematically showing aresistive tough panel. As shown in the drawing, the tough panel has astructure including the transparent conductive film (A) and a lower sidesubstrate (A′) that are opposed to each other with spacers (s)interposed therebetween.

The lower side substrate (A′) includes another transparent substrate(1′) and a transparent conductive layer (2′) placed thereon. It will beunderstood that the invention is not limited to this mode and, forexample, the transparent conductive film (A) may also be used to formthe lower side substrate (A′). The material used to form anothertransparent substrate (1′) may be basically a glass plate or the samematerial as used to form the substrate film (5). The thickness and otherfeatures of the substrate (1′) may also be the same as those of thesubstrate film (5). The material used to form another transparentconductive layer (2′) may be basically any of various transparentconductive layers, and another transparent conductive layer (2′) mayform the same structure as the transparent conductive laminate (2).

The spacers (s) may be of any insulating type, and various knownconventional spacers may be used. There is no particular limitation tothe method for production of the spacers (s), or the size, position, ornumber of the spacers (s). The spacers (s) to be used may have any knownconventional shape such as a substantially spherical shape or apolygonal shape.

The touch panel shown in FIG. 8 functions as a transparent switchsubstrate in which contact between the transparent conductive laminate(2) and the transparent conductive layer (2′) upon tapping with an inputpen or the like on the transparent conductive film (A) side against theelastic force of the spacers (s) produces the electrically on state,while removal of the press turns it to the original off state.

The film substrate (1) to be used may be any of various transparentplastic films with no particular limitation. Examples of materials forsuch films include polyester resins, acetate resins, polyether sulfoneresins, polycarbonate resins, polyamide resins, polyimide resins,polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins,polyvinylidene chloride resins, polystyrene resins, polyvinyl alcoholresins, polyarylate resins, and polyphenylene sulfide resins. Inparticular, polyester resins, polycarbonate resins, and polyolefinresins are preferred.

The thickness of the film substrate (1) is preferably in the range of 2to 200 μm, more preferably in the range of 2 to 120 μm, even morepreferably in the range of 2 to 100 μm. If the thickness of the filmsubstrate (1) is less than 2 μm, the film substrate (1) may haveinsufficient mechanical strength so that it may be difficult to performa process of continuously forming the transparent conductive laminate(2) and other layers such as the undercoat layer (3) and thepressure-sensitive adhesive layer (4) using a roll of the film substrate(1).

The surface of the film substrate (1) may be previously subjected tosputtering, corona discharge treatment, flame treatment, ultravioletirradiation, electron beam irradiation, chemical treatment, oxidation,or any other etching or undercoating treatment so that the transparentconductive laminate (2) or the undercoat layer (3) to be providedthereon can have improved adhesion to the film substrate (1). Ifnecessary, the film substrate may also be subjected to dust removing orcleaning by solvent cleaning, ultrasonic cleaning, or the like, beforethe transparent conductive laminate (2) or the undercoat layer (3) isformed thereon.

The surface of the film substrate (1), on which the transparentconductive laminate (2) will be formed, preferably has an arithmeticaverage roughness (Ra) of 1.0 nm or less, more preferably 0.7 nm orless, even more preferably 0.6 nm or less, in particular, preferably 0.5nm or less. When the surface roughness of the film substrate (1) isreduced, the transparent conductive laminate (2) can be crystallized byheating for a relatively short period of time, and after thecrystallization, the transparent conductive laminate (2) can have lowresistance. The lower limit of the arithmetic average surface roughness(Ra) of the transparent substrate is preferably, but not limited to, 0.1nm or more, more preferably 0.2 nm or more, from the standpoint ofimparting, to the substrate, the ability to be wound into a roll. Thearithmetic average roughness Ra may be measured using an atomic forcemicroscope (AFM) (NanoScope IV manufactured by Digital Instruments).

In general, films made of organic polymer formed products contain afiller or other materials for productivity or handleability andtherefore often have an arithmetic average surface roughness Ra ofseveral nm or more. To set the surface roughness of the film substrate(1) in the above range, the undercoat layer (3) is preferably formed onthe surface of the film substrate (1), on which the transparentconductive laminate (2) will be formed. When the undercoat layer (3) isformed on the surface of the film substrate (1), the irregularities ofthe surface of the film substrate (1) are reduced so that the surfaceroughness can be reduced.

It is relatively difficult to crystallize transparent conductive layersof indium-based complex oxides having a high content of a tetravalentmetal element oxide. However, when the film substrate (1) used has aspecific surface roughness as described above, even an amorphous secondtransparent conductive layer (22) formed using indium oxide or amaterial with a high content of a tetravalent metal element oxide can becompletely crystallized by a heat treatment for a relatively shortperiod of time.

The undercoat layer (3) shown in FIG. 3 may be formed using an inorganicmaterial, an organic material, or a mixture of inorganic and organicmaterials. Examples of inorganic materials that are preferably usedinclude SiOx (x=1 to 2), MgF₂, and Al₂O₃. Examples of organic materialsinclude acrylic resins, urethane resins, melamine resins, alkyd resins,siloxane polymers, and other organic substances. In particular, theorganic material is preferably a thermosetting resin including a mixtureof a melamine resin, an alkyd resin, and an organosilane condensate.

Using any of the above materials, the undercoat layer (3) may be formedby a dry process such as vacuum deposition, sputtering, or ion platingor a wet process (coating process). The undercoat layer (3) may be asingle layer or a laminate of two or more layers. In general, thethickness of the undercoat layer (3) (the thickness of each layer in thecase of a laminate of plural layers) is preferably from about 1 to about300 nm.

The transparent conductive laminate (2), which includes at least twotransparent conductive layers, is formed by a known thin film formingmethod such as vacuum deposition, sputtering, or ion plating, usingindium oxide or an indium-based complex oxide. While materials for usein forming such thin films are selected as appropriate depending on thethin film forming method, in general, sintered materials of indium oxideand a tetravalent metal element oxide are preferably used. In such athin film forming method as reactive sputtering, thin films may also beformed using indium metal and tin metal, while both metals are oxidized.

Examples of the tetravalent metal element include tin, cerium, hafnium,zirconium, and titanium. Oxides of these tetravalent metal elementsinclude tin oxide, cerium oxide, hafnium oxide, zirconium oxide, andtitanium oxide. Tin is preferably used as the tetravalent metal element.The tetravalent metal element oxide is preferably tin oxide, and theindium-based complex oxide is preferably an indium-tin complex oxide.

Sputtering methods that may be used to form the transparent conductivelaminate (2) include not only standard magnetron sputtering methodsusing a DC power source but also various sputtering methods such as RFsputtering, RF and DC sputtering, pulsed sputtering, and dual magnetronsputtering methods.

Such transparent conductive layers are stacked to form the transparentconductive laminate (2). In the formation, the ratio between indiumoxide and the tetravalent metal element oxide (or the ratio betweenindium metal and tetravalent metal), which are materials for forming thethin films, is selected, and the first transparent conductive layer (21)of indium oxide or an indium-based complex oxide having a tetravalentmetal element oxide content of more than 0% by weight and not more than6% by weight and the second transparent conductive layer (22) of anindium-based complex oxide having a tetravalent metal element oxidecontent higher than that of the first transparent conductive layer (21),wherein the tetravalent metal element oxide content is expressed by theformula: {the amount of the tetravalent metal element oxide/(the amountof the tetravalent metal element oxide+the amount of indiumoxide)}×100(%), are formed in such a manner that the first and secondtransparent conductive layers (21) and (22) are placed in this orderfrom the front surface side of the transparent conductive laminate (2)formed and that indium oxide or an indium-based complex oxide with alower content of the tetravalent metal element oxide is formed on thefront surface side.

The first transparent conductive layer (21) is preferably made of indiumoxide or an indium-based complex oxide having a tetravalent metalelement oxide content of more than 0% by weight and not more than 5% byweight. The content of the tetravalent metal element oxide in the firsttransparent conductive layer (21) on the front surface side ispreferably as specified above so that its crystallization can beaccelerated by a heat treatment at a low temperature for a short periodof time. If the content of the tetravalent metal element oxide in thefirst transparent conductive layer (21) is more than 6% by weight, theheat treatment process for its crystallization will be time-consuming.

The content of the tetravalent metal element oxide in the secondtransparent conductive layer (22) is set higher than the content of thetetravalent metal element oxide in the first transparent conductivelayer (21). The difference between the tetravalent metal element oxidecontents of the second transparent conductive layer (22) and the firsttransparent conductive layer (21) is preferably 3% by weight or morefrom the standpoint of reducing the specific resistance and thecrystallization time. The difference between the tetravalent metalelement oxide contents is more preferably from 3 to 35% by weight, evenmore preferably from 3 to 25% by weight, still more preferably from 5 to25% by weight. In general, the tetravalent metal element oxide contentof the second transparent conductive layer (22) is preferably from 3 to35% by weight, more preferably from 3 to 25% by weight, even morepreferably 5 to 25% by weight, still more preferably from 7 to 25% byweight, yet more preferably from 8 to 25% by weight.

From the standpoint of keeping the flexibility of the transparentconductive film high, the thickness of the first transparent conductivelayer (21) may be from 1 to 17 nm, preferably from 1 to 12 nm, morepreferably from 1 to 6 nm. The thickness of the second transparentconductive layer (22) is generally from 9 to 34 nm, preferably from 9 to29 nm, more preferably from 9 to 24 nm.

While the first and second transparent conductive layers (21) and (22)may each have a thickness in the above range, for a reduction inspecific resistance, the first and second transparent conductive layers(21) and (22) are preferably formed so that the first transparentconductive layer (21) has a thickness smaller than that of the secondtransparent conductive layer (22). From the standpoint of reducingspecific resistance, such a difference between the thicknesses of thefirst and second transparent conductive layers (21) and (22) ispreferably 1 nm or more, more preferably from 1 to 33 nm, even morepreferably from 1 to 20 nm.

The third transparent conductive layer (23) shown in FIG. 2 is providedindependently of the first and second transparent conductive layers (21)and (22). The third transparent conductive layer (23) may be made ofindium oxide or an indium-based complex oxide. The content of atetravalent metal element oxide in the third transparent conductivelayer (23) is not restricted and may be selected from the range of morethan 0% by weight and not more than 35% by weight. From the standpointof reducing the crystallization time, the content of the tetravalentmetal element oxide is preferably more than 0% by weight and not morethan 6% by weight, more preferably more than 0% by weight and not morethan 5% by weight similarly to the first transparent conductive layer(21). The thickness of the third transparent conductive layer (23) isgenerally from 1 to 17 nm, preferably from 1 to 12 nm, more preferablyfrom 1 to 6 nm. While FIG. 2 shows that a single layer of the thirdtransparent conductive layer (23) is provided on the film substrate (1)side, two or more layers of the third transparent conductive layers maybe formed independently of the first and second transparent conductivelayers (21) and (22).

As described above, the first transparent conductive layer (21) ispreferably provided in the uppermost part of the transparent conductivelaminate (2). On the other hand, any layer (not shown) that does notaffect the invention may also be provided on the front surface side ofthe first transparent conductive layer (21).

The transparent conductive laminate (2), which includes the first andsecond transparent conductive layers (21) and (22) as described above,preferably has a total thickness of 35 nm or less, more preferably 30 nmor less, so that it can have a high transmittance.

In order to reduce the specific resistance, the transparent conductivelaminate (2) is preferably designed so that the ratio of the thicknessof the first transparent conductive layer (21) to the total thickness ofthe transparent conductive laminate (2) is from 1 to 45%. The ratio ofthe thickness of the first transparent conductive layer (21) ispreferably from 1 to 30%, more preferably from 1 to 20%.

The sputtering target for use in the sputtering film formation isselected from indium oxide or an indium-based complex oxide, dependingon each thin film for the transparent conductive laminate (2). Inaddition, the content of the tetravalent metal element oxide in theindium-based complex oxide is controlled. The sputtering film formationusing such a target is performed in a sputtering system, which isevacuated to high vacuum and into which argon gas, an inert gas, isintroduced. When the sputtering target used is a metal target made ofindium or indium-tetravalent metal (for example, indium-tin), reactivesputtering film formation should be performed with argon gas introducedtogether with an oxidizing agent such as oxygen gas. Even when an oxidetarget such as indium oxide or an indium-based complex oxide is used,argon gas may also be introduced together with oxygen gas or the like.

Water molecules present in the film formation atmosphere may terminatedangling bonds, which are produced during the film formation, so thatthe crystal growth of indium oxide or an indium-based complex oxide maybe hindered. Therefore, the partial pressure of water in the filmformation atmosphere is preferably low. During the film formation, thewater partial pressure is preferably 0.1% or less, more preferably 0.07%or less, based on the partial pressure of argon gas. During the filmformation, the water partial pressure is also preferably 2×10⁻⁴ Pa orless, more preferably 1.5×10⁻⁴ Pa or less, even more preferably 1×10⁻⁴Pa or less. In order for the water partial pressure during the filmformation to be in the above range, the sputtering system before thestart of the film formation is preferably evacuated until the waterpartial pressure reaches 2×10⁻⁴ Pa or less, preferably 1.5×10⁻⁴ Pa orless, more preferably 1×10⁻⁴ Pa or less so as to fall within the aboverange so that impurities such as water and organic gas produced from thesubstrate can be removed from the atmosphere in the system.

During the sputtering film formation, the substrate temperature ispreferably higher than 100° C. When the substrate temperature is sethigher than 100° C., the crystallization of the indium-based complexoxide film (even with a high tetravalent metal atom content) can beeasily accelerated in the heat treatment process described below, and alow-resistance, crystalline, transparent conductive laminate (2) can beobtained. Therefore, in order to form a low-resistance, crystalline,transparent conductive laminate (2) in the process of crystallizing anamorphous transparent conductive laminate (2) by heating, the substratetemperature is preferably 120° C. or more, more preferably 130° C. ormore, in particular, preferably 140° C. or more. In order to suppressthermal damage to the substrate, the substrate temperature is preferably200° C. or less, more preferably 180° C. or less, even more preferably170° C. or less, in particular, preferably 160° C. or less.

As used herein, the term “substrate temperature” refers to the settemperature of a base on which the substrate is placed during thesputtering film formation. For example, when the sputtering filmformation is continuously performed in a roll-to-roll sputtering system,the substrate temperature corresponds to the temperature of a can rollon which the sputtering film formation is performed. When the sputteringfilm formation is performed by a piece-by-piece method (batch method),the substrate temperature corresponds to the temperature of a substrateholder for holding the substrate.

The transparent conductive film of the invention includes thetransparent conductive laminate (2) including: the first transparentconductive layer (21) of indium oxide or an indium-based complex oxidewith a specific content of a tetravalent metal element oxide; and thesecond transparent conductive layer (22) of an indium-based complexoxide in which the content of the tetravalent metal element oxide ishigher than that in the first transparent conductive layer (21), whichare placed in this order from the front surface side of the transparentconductive laminate (2), wherein the transparent conductive laminate (2)is a crystalline layer. The crystalline transparent conductive laminate(2) can be formed by a process including sequentially forming amorphoustransparent conductive layers and then performing an appropriate heattreatment to crystallize the amorphous transparent conductive laminate(2) so that a crystalline layer can be formed. The heat treatment may beperformed using heating means such as an infrared heater or a hot-aircirculation oven according to known methods. In such a process, the heattreatment temperature should be 150° C. or less, which is acceptable tothe film substrate. In an embodiment of the invention, a heat treatmentat such a low temperature for a short period of time can achievesufficient crystallization. Specifically, a heat treatment at 150° C.for a time period of 2 hours or less enables the formation of ahigh-quality crystalline layer.

In the heat treatment process, the heating temperature is preferablyfrom 120° C. to 150° C., more preferably from 125° C. to 150° C., evenmore preferably from 130° C. to 150° C. The sufficient heating time canbe reduced to less than 60 minutes and further reduced to 45 minutes orless, so that the crystallization time can be reduced. When the heatingtemperature and the heating time are appropriately selected, the filmcan be completely crystallized with no reduction in productivity orquality. In order to crystallize the amorphous transparent conductivelaminate (2) completely, the heating is preferably performed for a timeperiod of 30 minutes or more.

When the transparent conductive film is used to form a projection-typecapacitance touch panel, a matrix-type resistive touch panel, or anyother touch panel, the transparent conductive laminate (2) is patternedinto a specific shape (for example, a strip shape) in some cases.However, when crystallized by the heat treatment, the indium oxide filmor the indium-based complex oxide film is less susceptible to an etchingprocess with an acid. In contrast, the amorphous indium oxide orindium-based complex oxide film before the heat treatment can be easilyprocessed by etching. Therefore, when the transparent conductivelaminate (2) is patterned by etching, the transparent conductivelaminate (2) should preferably be subjected to the etching process afterthe film formation before the heat treatment process.

A transparent pressure-sensitive adhesive layer (4) may be provided onthe other surface of the film substrate (1). The transparentpressure-sensitive adhesive layer (4) may be of any type havingtransparency. Specific examples include transparent pressure-sensitiveadhesive layers including, as a base polymer, an acryl-based polymer, asilicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, avinyl acetate-vinyl chloride copolymer, modified polyolefin, an epoxypolymer, a fluoropolymer, rubber such as natural rubber or syntheticrubber, or any other polymer, which may be appropriately selected andused. In particular, an acryl-based pressure-sensitive adhesive ispreferably used because it has high optical transparency and anappropriate level of adhesive properties such as wettability,cohesiveness, and tackiness.

The pressure-sensitive adhesive layer (4) has a cushion effect and thuscan function to improve the scratch resistance of the transparentconductive laminate (2) formed on one side of the film substrate (1) andto improve tap properties, so-called pen input durability and contactpressure durability, for touch panels. In order to perform this functionbetter, it is preferred that the elastic modulus of thepressure-sensitive adhesive layer (4) should be set in the range of 1 to100 N/cm² and that its thickness should be set to 1 μm or more,generally in the range of 5 to 100 μm.

If the thickness of the pressure-sensitive adhesive layer (4) is lessthan 1 μm, the cushion effect can no longer be expected, so that it willtend to be difficult to improve the scratch resistance of thetransparent conductive laminate (2) or pen input durability and contactpressure durability for touch panels. On the other hand, if it is toothick, it may have reduced transparency, or good results may bedifficult to obtain with respect to the formation of thepressure-sensitive adhesive layer (4), the bonding workability, and thecost.

EXAMPLES

Hereinafter, the invention is described in more detail with reference tothe examples, which however are not intended to limit the gist of theinvention. In each example, all parts are by weight unless otherwisespecified.

(Arithmetic Average Roughness)

The arithmetic average roughness was measured using an atomic forcemicroscope (AFM) (NanoScope IV manufactured by Digital instruments).

Example 1

A 30 nm thick undercoat layer of a thermosetting resin composed of amelamine resin, an alkyd resin, and an organosilane condensate (2:2:1 inweight ratio) was formed on one surface of a film substrate made of a 23μm thick polyethylene terephthalate film (hereinafter referred to as PETfilm). The surface of the undercoat layer had an arithmetic averageroughness Ra of 0.5 nm.

A 20 nm thick transparent conductive layer of an indium-tin complexoxide was formed on the undercoat layer by a reactive sputtering methodusing a sintered material of 90% indium oxide and 10% tin monoxide in a0.4 Pa atmosphere composed of 80% by volume of argon gas and 20% byvolume of oxygen gas. The film formation process included evacuating thesputtering system until the water partial pressure at the time of filmformation reached 8.0×10⁻⁵ Pa, then introducing argon gas and oxygengas, and forming the film at a substrate temperature of 140° C. in anatmosphere with a water partial pressure of 8.0×10⁻⁵ Pa. At this time,the water partial pressure was 0.05% of the partial pressure of theargon gas. The resulting transparent conductive layer corresponds to thesecond transparent conductive layer (22), which is located second fromthe uppermost surface in FIG. 1.

A 5 nm thick transparent conductive layer of an indium-tin complex oxidewas formed on the resulting transparent conductive layer by a reactivesputtering method using a sintered material of indium oxide. The filmformation process included evacuating the sputtering system until thewater partial pressure at the time of film formation reached 8.0×10⁻⁵Pa, then introducing argon gas and oxygen gas, and forming the film at asubstrate temperature of 140° C. in an atmosphere with a water partialpressure of 8.0×10⁻⁵ Pa. At this time, the water partial pressure was0.05% of the partial pressure of the argon gas. The resultingtransparent conductive layer corresponds to the first transparentconductive layer (21) which is located first from the uppermost surfacein FIG. 1.

In this way, a transparent conductive laminate including first andsecond amorphous transparent conductive layers was formed to obtain atransparent conductive film. Subsequently, the resulting transparentconductive film was heat-treated at 140° C. in a hot-air circulationoven so that the transparent conductive laminate was crystallized.

Examples 2 to 7 and 9 to 13

Transparent conductive films were prepared as in Example 1, except thatthe content of tin oxide in the sintered indium oxide-tin oxide materialand the thickness of each layer, which were used in the formation of thefirst and second transparent conductive layers, were changed as shown inTable 1. Each transparent conductive laminate was also crystallized asin Example 1. In Table 1, “tin oxide content” indicates the content oftin oxide in the indium oxide or indium-tin complex oxide material usedas the sputtering target. A tin oxide content of “0%” indicates the caseusing indium oxide. The thickness of the transparent conductive layerindicates the thickness before the crystallization. The content of tinoxide and the thickness of the transparent conductive layer areconsidered to be unchanged even after the crystallization.

Example 8

An undercoat layer was formed on one surface of a film substrate as inExample 1. A 3 nm thick transparent conductive layer of an indium-tincomplex oxide was formed on the undercoat layer by a reactive sputteringmethod using a sintered material of 97% indium oxide and 3% tin monoxidein a 0.4 Pa atmosphere composed of 80% by volume of argon gas and 20% byvolume of oxygen gas. The film formation process included evacuating thesputtering system until the water partial pressure at the time of filmformation reached 8.0×10⁻⁵ Pa, then introducing argon gas and oxygengas, and forming the film at a substrate temperature of 140° C. in anatmosphere with a water partial pressure of 8.0×10⁻⁵ Pa. At this time,the water partial pressure was 0.05% of the partial pressure of theargon gas. The resulting transparent conductive layer corresponds to thethird transparent conductive layer (23) which is located third from theuppermost surface in FIG. 2.

A 19 nm thick transparent conductive layer of an indium-tin complexoxide was further formed on the resulting transparent conductive layerby a reactive sputtering method using a sintered material of 90% indiumoxide and 10% tin monoxide. The film formation process includedevacuating the sputtering system until the water partial pressure at thetime of film formation reached 8.0×10⁻⁵ Pa, then introducing argon gasand oxygen gas, and forming the film at a substrate temperature of 140°C. in an atmosphere with a water partial pressure of 8.0×10⁻⁵ Pa. Atthis time, the water partial pressure was 0.05% of the partial pressureof the argon gas. The resulting transparent conductive layer correspondsto the second transparent conductive layer (22) which is located secondfrom the uppermost surface in FIG. 2.

A 3 nm thick transparent conductive layer of an indium-tin complex oxidewas further formed on the resulting transparent conductive layer by areactive sputtering method using a sintered material of 97% indium oxideand 3% tin monoxide. The film formation process included evacuating thesputtering system until the water partial pressure at the time of filmformation reached 8.0×10⁻⁵ Pa, then introducing argon gas and oxygengas, and forming the film at a substrate temperature of 140° C. in anatmosphere with a water partial pressure of 8.0×10⁻⁵ Pa. At this time,the water partial pressure was 0.05% of the partial pressure of theargon gas. The resulting transparent conductive layer corresponds to thefirst transparent conductive layer (21) which is located first from theuppermost surface in FIG. 2.

In this way, a transparent conductive laminate including first, second,and third amorphous transparent conductive layers was formed to obtain atransparent conductive film. Subsequently, the resulting transparentconductive film was heat-treated at 140° C. in a hot-air circulationoven so that the transparent conductive laminate was crystallized.

Comparative Example 1

An undercoat layer was formed on one surface of a film substrate as inExample 1. A 25 nm thick amorphous transparent conductive layer of anindium-tin complex oxide was formed on the undercoat layer by a reactivesputtering method using a sintered material of 90% indium oxide and 10%tin monoxide in a 0.4 Pa atmosphere composed of 80% by volume of argongas and 20% by volume of oxygen gas. Subsequently, the resultingtransparent conductive film was heat-treated at 150° C. in a hot-aircirculation oven so that the transparent conductive laminate wascrystallized.

Comparative Examples 2 to 5

Amorphous transparent conductive films were prepared as in Example 1,except that the content of tin oxide in the sintered indium oxide-tinoxide material and the thickness of each layer, which were used in theformation of the first and second transparent conductive layers, werechanged as shown in Table 1. Each transparent conductive laminate wasalso crystallized as in Example 1. The crystallization time is shown inTable 1.

(Evaluation)

The transparent conductive films obtained in the examples and thecomparative examples were evaluated as described below. The results areshown in Table 1.

<Thickness of Each Layer>

The thickness of the film substrate was measured with a microgauge typethickness gauge manufactured by Mitutoyo Corporation. The thickness ofeach of the undercoat layer and the transparent conductive layer wascalculated using an instantaneous multichannel photodetector systemMCPD-2000 (trade name) manufactured by Otsuka Electronics Co., Ltd.,based on the waveform data on the resulting interference spectrum.

<Crystallization Time>

In each example, the time (minutes) required to crystallize thetransparent conductive layer (laminate) was measured. The heating wasperformed at 140° C. using a hot-air circulation oven, and whether thetransparent conductive layer (laminate) was crystallized was determinedby “checking the completion of the change (reduction) in resistancevalue” and performing an “etching test” as described below.

-   “Checking the completion of the change (reduction) in resistance    value”: While the heating was performed at 140° C. using a hot-air    circulation oven, the surface resistance value was measured every 30    minutes. As the crystallization proceeds, the surface resistance    value decreases, and when the crystallization is completed, the    surface resistance value becomes constant. Therefore, the    crystallization time was determined at the time when the surface    resistance value became constant.-   “Etching test”: The transparent conductive laminate was immersed in    hydrochloric acid with a concentration of 5% by weight for 15    minutes, and then the resistance value (Ω) between two points 15 mm    apart was measured using a tester (DIGITAL TESTER (M-04) (product    name) manufactured by CUSTOM, measurement limit: 2 MΩ) to determine    whether or not the transparent conductive layer (laminate) was    crystallized. When a certain resistance value was detected, it was    determined that the transparent conductive layer (laminate) was    crystallized.    <Surface Resistance>

The surface resistance (Ω/square) of the transparent conductive layer ineach transparent conductive film was measured using a four-terminalmethod.

<Specific Resistance>

The thickness of the transparent conductive layer (laminate) wasmeasured using an X-ray fluorescence analyzer (manufactured by RigakuCorporation), and the specific resistance was calculated from thesurface resistance and the thickness.

TABLE 1 Transparent conductive layer (laminate) First from uppermostsurface Second from Third from Tin uppermost surface uppermost surfaceEvaluation oxide Tin oxide Tin oxide Total Crystallization SurfaceSpecific content Thickness content Thickness content Thickness thicknesstime resistance resistance (wt %) (nm) (wt %) (nm) (wt %) (nm) (nm)(minutes) (Ω/square) (Ω · cm) Example 1 0 5 10 20 — — 25 30 150 3.75 ×10⁻⁴ Example 2 0 5 15 20 — — 25 30 130 3.25 × 10⁻⁴ Example 3 0 5 35 20 —— 25 45 130 3.25 × 10⁻⁴ Example 4 3 5 10 20 — — 25 30 130 3.25 × 10⁻⁴Example 5 3 10 10 15 — — 25 30 140 3.50 × 10⁻⁴ Example 6 3 3 10 22 — —25 30 130 3.25 × 10⁻⁴ Example 7 3 13 10 12 — — 25 30 150 3.75 × 10⁻⁴Example 8 3 3 10 19 3 3 25 30 130 3.25 × 10⁻⁴ Example 9 3 5 15 20 — — 2530 130 3.25 × 10⁻⁴ Example 10 3 5 35 20 — — 25 45 130 3.25 × 10⁻⁴Example 11 6 5 10 20 — — 25 30 140 3.50 × 10⁻⁴ Example 12 6 5 15 20 — —25 30 130 3.25 × 10⁻⁴ Example 13 6 5 35 20 — — 25 45 130 3.25 × 10⁻⁴Comparative 10 25 — — — — 25 90 150 3.75 × 10⁻⁴ Example 1 Comparative 1020 3 5 — — 25 60 150 3.75 × 10⁻⁴ Example 2 Comparative 8 5 10 20 — — 2590 140 3.50 × 10⁻⁴ Example 3 Comparative 8 5 15 20 — — 25 120 130 3.25 ×10⁻⁴ Example 4 Comparative 8 5 35 20 — — 25 >120 — — Example 5

It is apparent that the crystallization time is shorter in the examplesthan in the comparative examples. It is also apparent that when thethickness of the first transparent conductive layer (21) is controlledto be smaller than the thickness of the second transparent conductivelayer (22) as in the examples, the surface resistance and the specificresistance can be reduced.

What is claimed is:
 1. A transparent conductive film, comprising: atransparent film substrate; and a transparent conductive laminate havinga total thickness of 35 nm or less that is provided on at least onesurface of the transparent film substrate and comprises a firsttransparent conductive layer and a second transparent conductive layer,wherein the first transparent conductive layer is a first crystallinelayer comprising indium oxide or an indium-based complex oxide having atetravalent metal element oxide, a first content of the tetravalentmetal element oxide of the first transparent conductive layer is morethan 0% by weight and not more than 6% by weight, the second transparentconductive layer is a second crystalline layer comprising anindium-based complex oxide having a tetravalent metal element oxide, andlocated between the transparent film substrate and the first transparentconductive layer, and a second content of the tetravalent metal elementoxide of the second transparent conductive layer is higher than thefirst content, wherein each of the first and the second contents of thetetravalent metal element oxide content is expressed by the formula:{the amount of the tetravalent metal element oxide/(the amount of thetetravalent metal element oxide+the amount of indium oxide)}×100(%). 2.The transparent conductive film according to claim 1, wherein adifference between the first content and the second content is 3% byweight or more.
 3. The transparent conductive film according to claim 1,wherein the second content is 3 to 35% by weight.
 4. The transparentconductive film according to claim 1, wherein a first thickness of thefirst transparent conductive layer is smaller than a second thickness ofthe second transparent conductive layer.
 5. The transparent conductivefilm according to claim 4, wherein a difference between the firstthickness and the second thickness is 1 nm or more.
 6. The transparentconductive film according to claim 1, wherein a first thickness of thefirst transparent conductive layer is 1 to 17 nm, and a second thicknessof the second transparent conductive layer is 9 to 34 nm.
 7. Thetransparent conductive film according to claim 1, further comprising athird transparent conductive layer that is located between thetransparent film substrate and the second transparent conductive layer,and the third transparent conductive layer is a third crystalline layer.8. The transparent conductive film according to claim 7, wherein thethird transparent conductive layer comprises indium oxide or anindium-based complex oxide having a tetravalent metal element oxide, anda third content of the tetravalent metal element oxide of the thirdtransparent conductive layer is more than 0% by weight and not more than6% by weight, wherein the third content is expressed by the formula:{the amount of the tetravalent metal element oxide/(the amount of thetetravalent metal element oxide+the amount of indium oxide)}×100(%). 9.The transparent conductive film according to claim 1, wherein a ratio ofthe first thickness to the total thickness is from 1 to 45%.
 10. Thetransparent conductive film according to claim 1, wherein theindium-based complex oxide is an indium-tin complex oxide, and thetetravalent metal element oxide is tin oxide.
 11. The transparentconductive film according to claim 1, wherein the transparent conductivelaminate is provided on the film substrate with an undercoat layerinterposed therebetween.
 12. A touch panel, comprising the transparentconductive film according to claim 1.